A semiconductor device contains a semiconductor chip. The chip is a main portion of the device. The semiconductor chip has various elements, wiring patterns, functional blocks, bonding pads and the others. A semiconductor wafer is prepared when the semiconductor chip is manufactured. After a semiconductor wafer manufacturing process is completed, the wafer is separated by cutting or dicing to be individual chips (an individual separation), and, for example, the semiconductor chip is bonded on a package substrate such as a lead frame or an interposer. The bonding pads on a surface of the semiconductor chip bonded on the lead frame are connected to the lead frame by wires. The semiconductor chip, a portion of the lead frame, the wires, and others are molded by resin.
Japanese Patent Laid-Open No. 2003-188193 discloses a conventional method of fixing a semiconductor chip in a predetermined position on a lead frame. According to Japanese Patent Laid-Open No. 2003-188193, a semiconductor wafer with an adhesive tape is separated by cutting to semiconductor chips, and the adhesive tape with the semiconductor chips is placed on a chip supply table. The chip should be correctly placed in a predetermined position so that it is placed in the correct position under a bonding operation. An image of the semiconductor chip which is to be bonded is captured on the adhesion tape by a chip recognition camera over the semiconductor chip. The image is compared with that of a reference chip placed in a reference position captured beforehand Then a difference in position between the semiconductor chip and the reference chip is calculated. A position of an adsorption nozzle of a conveyance mechanism is corrected based on the difference, then the adsorption nozzle is moved to the position of the semiconductor chip, and the semiconductor chip is adsorbed. The adsorbed semiconductor chip is moved to and placed over the predetermined position of the lead frame by an arm of the conveyance mechanism movable in three dimensions (X, Y and Z). The adsorbed semiconductor chip is moved down and reaches on the lead frame, and it is bonded to the lead frame with an adhesive material.
After the semiconductor chip has been positioned before being adsorbed, the position of the semiconductor chip may not be checked or corrected until it is released, since the adsorption nozzle may interrupt the field of view of the chip recognition camera while the semiconductor chip is being adsorbed. That is, after increasing inaccuracy of the position, the semiconductor chip adheres to the lead frame.
It is difficult to adsorb semiconductor chips consistently in the same position of a tip of the adsorption nozzle under reduced pressure, as an air flow occurs and it often shifts a semiconductor chip in an unspecified direction from a predetermined position. Therefore, the adhered semiconductor chip may be shifted from the predetermined position of the lead frame. This unintentional shift affects the ensuing processes. At a wire-bonding process, for example, corrections of bonding positions based on the shift of the semiconductor chip become necessary. This correction process may require an increased process time and may result in an increase in defective wire-bonding.
Moreover, in order to recognize the position of the semiconductor chip, the method of fixing the semiconductor chip requires that images of the reference chip beforehand be captured and recorded, and that the most suitable image be selected and compared with the image of the semiconductor chip. And whenever images of semiconductor chips change, an excess process time when images of the related reference chips are captured become necessary.
Certain methods for positioning a semiconductor device in a predetermined position on a package substrate are known. Japanese Patent No. 2709631 describes a photoelectromagnetic device having a photoelectric element to convert optical signals into current signals and a magnetic path in which magnetic flux is produced by passing the current signals in a thin film coil.
Japanese Patent Laid-Open No. H9-209970 describes a fluid driving method and device changing periodically directions of magnetic lines of force by passing current on a coil and switching the direction of the current periodically.
Japanese Patent Laid-Open No. 2001-179700 describes a movement control system of a micro machine having a magnetic field generation unit which generates a rotating field and performing a directional control by magnetic field change means.
Japanese Patent Laid-Open No. H11-113239 describes a linear motor having coils approximately equalized amount of reverse electromotive current generated in each coil when the parallel-connection coils move relatively in a magnetic field.
These conventional approaches use magnetic fields as driving forces. However, there is no teaching or suggestion of applying them to move a semiconductor chip itself to a predetermined position.